A3 1.8TSport spluttering - Help needed!!!

[rjcowan]

Hi

I am a newbie to this forum but I have a problem with my 98 A3. Due to my heavy right foot and clearly poor judgement I managed to run the car out of petrol. Managed to get some more petrol and ran through half a tank when an intermittant problem has started occuring. Sometimes the at idle the revs drop below 800 then come back again. When i accelerate the car feels like someone is giving the car power then taking it away. As you get faster this shuddering still exists but is not that noticeably unless you drop into third and put the pedal down. After a while it will clear and everything is fine.

It doesn't happen all the time which is more annoying. Somoeone mentioned that it could be my DV (divertor valve) but I have no idea what that is.

Can anyone help??? I have tried putting the injector cleaner in the petrol and it seemed to help but it could just be my imagination.

 

[Mike.M]

Could have a coil pack going or gone....common thing unfortunately.

If the DV went it would make weird chirping noises.

 

[cybrey]

I'm not expert but from I've been told theres normally quite a lot of rubbish sitting at the bottom of petrol tanks which is why ppl are advised not to run them emtpy.

This gunk is dragged through the engine, I suspect this is why you noticed an improvement when you put some injector cleaner in. There's a product, which I can't remember the name of atm, which cleans everything ( allegedly). When I remember the name it may be worth sticking some of this in to see if it clears up the problem.

 

[rjcowan]

Thanks Guys. I have been looking through the posts on coil packs. The sympton I have in common is that when this problem happens and I get out of the car I can smell burnt rubber. Thought it was me getting paranoid.
What do the Coil packs do, how many are there and are they easy to replace?

 

[Mike.M]

similar to a spark plug to fire the fuel in each cylinder just AUDI/VW/SKODA/SEAT design.

Cost about £15-£20 each............simple twist of about 2.5 turns to put in or out.

 

[Mike.M]

its just trying to find which one or more it is?

 

[rjcowan]

Many thanks. I am away to speak to my mechanic and see what he can do.

 

[jimboA3]

That sounds like a faulty maf sensor to me . Same as mine was was when that went.

 

[benk]

From the basic info I've seen on here before, coilpacks usually mean seriously slow and low power car, sometimes undriveable, MAF is usually a problem at higher boost (no power above 4000 rpm), diverter valve leaking will start with audible noise from turbo between gear changes.
I'd agree that you've got fuel tank crap in your tubes and it's interrupting the flow, causing the delivery of fuel to flick up/down or on/off, which would explain why you get jerks at random, etc. Have you tried calling a garage to mention the symptoms - they might say "yeah, crap in your pipes, probably needs a clean-out" - any comments they have might give you more idea of the problem.

 

[rjcowan]

Excuse my poor mechanical knowledge which i am trying to improve. What is the MAF? where is it and where do u get your parts from

 

[MingBluS3]

how can you test or tell if you have a faulty MAF sensor? and why would the stealer choose to replace it?

 

[benk]

the MAF is inside the airbox - do a search in this site and you'll find out all you need to know about it. I think the basics are that the MAF monitors airflow into the car, and the lambda sensors (oxygen sensors) in your exhaust monitor the air exiting the car. By knowing how much air you're sucking in and how much oxygen you aren't burning, the car knows what it needs to in order to control the fuel/air ratio it supplies to the engine.

 

[V1RDE]

Stepper motor? or could be any of the above. Sounds like the stepper motor, as your revs are dying then picking up and the car is stuttering. Clean it or have it replaced. Should sort out the problem.

 

[ooooaudi]

Exactly the same symtoms as mine had.....
try the connections to the coil pack control unit ( not sure its proper name ) thats located on the back of the air filter box.

this happend to mine, all i did was disconnect the two plugs tightend up the connectors and clean'd them all, reconnected and car was sorted !

the MAF is located on the plastic pipe coming from the air box going to the turbo inlet.